1. Field of the Invention
The present invention relates to an Internet Protocol (IP) network-based headend system and an operating method thereof, and relates to a quadrature amplitude modulation (QAM) pre-processing device.
2. Description of the Related Art
As users are constantly changed in a broadcast communication system market, a broadcast service provider attempts to provide various services to cope with the changes of the users. As one of the attempts, the broadcast service provider may provide a broadcast service to a user and may also provide an interactive service that provides broadcast service to the user in response to a request of the user.
To provide the interactive service, an Internet Protocol (IP) network-based wireless communication system using a multicasting scheme has been introduced. Specifically, a system that equips a Data Over Cable Service Interface Specification (DOCSIS) standard-based cable modem termination device in a headend side to transmit a video data stream to a device in a receiving side has been developed. However, the video data stream has a feature of a real-time transmission and has a high capacity and thus, a plurality of cable modem termination devices may need to be included in the headend side to process the video data stream.
In a conventional headend system, a headend side is mainly configured by a quadrature amplitude modulator and thus, the quadrature amplitude modulator may need to be changed with the plurality of cable modem terminal devices. However, the cable modem terminal device is expensive, and cost may also be expended for implementation and thus, a financial burden may be incurred due to the changing of the quadrature amplitude modulator with the plurality of cable modem terminal devices.